Line data    Source code

       1              : //! Salted Challenge Response Authentication Mechanism.
       2              : //!
       3              : //! RFC: <https://datatracker.ietf.org/doc/html/rfc5802>.
       4              : //!
       5              : //! Reference implementation:
       6              : //! * <https://github.com/postgres/postgres/blob/94226d4506e66d6e7cbf4b391f1e7393c1962841/src/backend/libpq/auth-scram.c>
       7              : //! * <https://github.com/postgres/postgres/blob/94226d4506e66d6e7cbf4b391f1e7393c1962841/src/interfaces/libpq/fe-auth-scram.c>
       8              : 
       9              : mod countmin;
      10              : mod exchange;
      11              : mod key;
      12              : mod messages;
      13              : mod pbkdf2;
      14              : mod secret;
      15              : mod signature;
      16              : pub mod threadpool;
      17              : 
      18              : use base64::Engine as _;
      19              : use base64::prelude::BASE64_STANDARD;
      20              : pub(crate) use exchange::{Exchange, exchange};
      21              : use hmac::{Hmac, Mac};
      22              : pub(crate) use key::ScramKey;
      23              : pub(crate) use secret::ServerSecret;
      24              : use sha2::{Digest, Sha256};
      25              : 
      26              : const SCRAM_SHA_256: &str = "SCRAM-SHA-256";
      27              : const SCRAM_SHA_256_PLUS: &str = "SCRAM-SHA-256-PLUS";
      28              : 
      29              : /// A list of supported SCRAM methods.
      30              : pub(crate) const METHODS: &[&str] = &[SCRAM_SHA_256_PLUS, SCRAM_SHA_256];
      31              : pub(crate) const METHODS_WITHOUT_PLUS: &[&str] = &[SCRAM_SHA_256];
      32              : 
      33              : /// Decode base64 into array without any heap allocations
      34           49 : fn base64_decode_array<const N: usize>(input: impl AsRef<[u8]>) -> Option<[u8; N]> {
      35           49 :     let mut bytes = [0u8; N];
      36              : 
      37           49 :     let size = BASE64_STANDARD.decode_slice(input, &mut bytes).ok()?;
      38           49 :     if size != N {
      39            0 :         return None;
      40           49 :     }
      41              : 
      42           49 :     Some(bytes)
      43           49 : }
      44              : 
      45              : /// This function essentially is `Hmac(sha256, key, input)`.
      46              : /// Further reading: <https://datatracker.ietf.org/doc/html/rfc2104>.
      47           15 : fn hmac_sha256<'a>(key: &[u8], parts: impl IntoIterator<Item = &'a [u8]>) -> [u8; 32] {
      48           15 :     let mut mac = Hmac::<Sha256>::new_from_slice(key).expect("bad key size");
      49           75 :     parts.into_iter().for_each(|s| mac.update(s));
      50              : 
      51           15 :     mac.finalize().into_bytes().into()
      52           15 : }
      53              : 
      54           12 : fn sha256<'a>(parts: impl IntoIterator<Item = &'a [u8]>) -> [u8; 32] {
      55           12 :     let mut hasher = Sha256::new();
      56           12 :     parts.into_iter().for_each(|s| hasher.update(s));
      57              : 
      58           12 :     hasher.finalize().into()
      59           12 : }
      60              : 
      61              : #[cfg(test)]
      62              : mod tests {
      63              :     use super::threadpool::ThreadPool;
      64              :     use super::{Exchange, ServerSecret};
      65              :     use crate::intern::EndpointIdInt;
      66              :     use crate::sasl::{Mechanism, Step};
      67              :     use crate::types::EndpointId;
      68              : 
      69              :     #[test]
      70            1 :     fn snapshot() {
      71            1 :         let iterations = 4096;
      72            1 :         let salt = "QSXCR+Q6sek8bf92";
      73            1 :         let stored_key = "FO+9jBb3MUukt6jJnzjPZOWc5ow/Pu6JtPyju0aqaE8=";
      74            1 :         let server_key = "qxJ1SbmSAi5EcS0J5Ck/cKAm/+Ixa+Kwp63f4OHDgzo=";
      75            1 :         let secret = format!("SCRAM-SHA-256${iterations}:{salt}${stored_key}:{server_key}",);
      76            1 :         let secret = ServerSecret::parse(&secret).unwrap();
      77              : 
      78              :         const NONCE: [u8; 18] = [
      79              :             1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
      80              :         ];
      81            1 :         let mut exchange =
      82            1 :             Exchange::new(&secret, || NONCE, crate::tls::TlsServerEndPoint::Undefined);
      83              : 
      84            1 :         let client_first = "n,,n=user,r=rOprNGfwEbeRWgbNEkqO";
      85            1 :         let client_final = "c=biws,r=rOprNGfwEbeRWgbNEkqOAQIDBAUGBwgJCgsMDQ4PEBES,p=rw1r5Kph5ThxmaUBC2GAQ6MfXbPnNkFiTIvdb/Rear0=";
      86            1 :         let server_first =
      87            1 :             "r=rOprNGfwEbeRWgbNEkqOAQIDBAUGBwgJCgsMDQ4PEBES,s=QSXCR+Q6sek8bf92,i=4096";
      88            1 :         let server_final = "v=qtUDIofVnIhM7tKn93EQUUt5vgMOldcDVu1HC+OH0o0=";
      89              : 
      90            1 :         exchange = match exchange.exchange(client_first).unwrap() {
      91            1 :             Step::Continue(exchange, message) => {
      92            1 :                 assert_eq!(message, server_first);
      93            1 :                 exchange
      94              :             }
      95            0 :             Step::Success(_, _) => panic!("expected continue, got success"),
      96            0 :             Step::Failure(f) => panic!("{f}"),
      97              :         };
      98              : 
      99            1 :         let key = match exchange.exchange(client_final).unwrap() {
     100            1 :             Step::Success(key, message) => {
     101            1 :                 assert_eq!(message, server_final);
     102            1 :                 key
     103              :             }
     104            0 :             Step::Continue(_, _) => panic!("expected success, got continue"),
     105            0 :             Step::Failure(f) => panic!("{f}"),
     106              :         };
     107              : 
     108            1 :         assert_eq!(
     109            1 :             key.as_bytes(),
     110              :             [
     111              :                 74, 103, 1, 132, 12, 31, 200, 48, 28, 54, 82, 232, 207, 12, 138, 189, 40, 32, 134,
     112              :                 27, 125, 170, 232, 35, 171, 167, 166, 41, 70, 228, 182, 112,
     113              :             ]
     114              :         );
     115            1 :     }
     116              : 
     117            2 :     async fn run_round_trip_test(server_password: &str, client_password: &str) {
     118            2 :         let pool = ThreadPool::new(1);
     119              : 
     120            2 :         let ep = EndpointId::from("foo");
     121            2 :         let ep = EndpointIdInt::from(ep);
     122              : 
     123            2 :         let scram_secret = ServerSecret::build(server_password).await.unwrap();
     124            2 :         let outcome = super::exchange(&pool, ep, &scram_secret, client_password.as_bytes())
     125            2 :             .await
     126            2 :             .unwrap();
     127              : 
     128            2 :         match outcome {
     129            1 :             crate::sasl::Outcome::Success(_) => {}
     130            1 :             crate::sasl::Outcome::Failure(r) => panic!("{r}"),
     131              :         }
     132            1 :     }
     133              : 
     134              :     #[tokio::test]
     135            1 :     async fn round_trip() {
     136            1 :         run_round_trip_test("pencil", "pencil").await;
     137            1 :     }
     138              : 
     139              :     #[tokio::test]
     140              :     #[should_panic(expected = "password doesn't match")]
     141            1 :     async fn failure() {
     142            1 :         run_round_trip_test("pencil", "eraser").await;
     143            1 :     }
     144              : }